Work vehicles (including, but not limited to, agricultural work vehicles such as tractors and combines as well as construction equipment vehicles such as loader-backhoes) can be configured to automatically perform sequences of operations. Such automatic sequences of operations (also known as "macros") facilitate the operation of the work vehicles by their operators. The macro allows the operator of a work vehicle to command multiple functions simultaneously or in rapid succession by actuating a single input device. In the absence of such an automatic sequence of operations, the operator would be required to manually activate and/or control each of the multiple functions. This activation and/or control of multiple functions within a short time by the operator may require a high level of skill or concentration, may lead to increased operator fatigue or, in some cases, may not be possible. Yet through the implementation of an automatic sequence of operations, the operator of the work vehicle can cause many functions to take place at the "push of a button" (or at some point following the push of a button) with minimal effort or concentration on the operator's part.
Such automatic sequences of operations are useful in many contexts. For example, an agricultural tractor is often required to perform multiple operations repeatedly at the end of each row of a field as the tractor traverses the field. These functions may include (a) raising or lowering a hitch, or an implement being towed by the tractor, (b) raising or lowering one or more field markers associated with the tractor, (c) disabling or enabling a power take-off shaft providing power to a towed implement, (d) deactivating or activating the distribution of seeds, insecticide or other farming input being applied to the field, (e) disengaging or engaging a mechanical four-wheel drive ("MFD") mechanism or a differential locking ("DL") mechanism, (f) decreasing or increasing the setting of the engine throttle, (g) shifting the gear ratio between the input and output of a transmission of the tractor and (h) activating or deactivating an automatic steering routine. Given the number and complexity of these operations at the end of a row, an automatic performance of some or all of these operations can facilitate the operation of the work vehicle by its operator and reduce the likelihood of operator error.
In the construction equipment vehicle field, a loader-backhoe, for example, may be required to perform the same or similar movements repeatedly as the loader-backhoe excavates a hole. These movements may include (a) lowering a boom assembly of the loader-backhoe from a raised position above a hole into the hole, (b) retracting a bucket of the boom assembly so that the bucket scoops up soil or other material, (c) raising the boom assembly to a raised position again, (d) repositioning the boom assembly so that the bucket is positioned over a hauling (dump) truck, (e) extending the bucket so that the material in the bucket is dropped into the hauling truck and (f) repositioning the boom assembly so that it is positioned over the hole. Controlling these movements requires significant concentration on the part of the operator of the loader-backhoe and, except in the case of a highly skilled operator, may be very time-consuming. An automatically-performed sequence of operations in this context facilitates the operation of the loader-backhoe by its operator. By automating such operations, the speed of the process of excavating a hole and placing the excavated material into a hauling truck can be increased considerably.
Implementation of such automatic sequences of operations on a work vehicle requires sophisticated electronic control mechanisms. Such electronic control mechanisms typically employ one or more electronic control units connected with one another and/or with controlled devices, input devices, communications devices, sensors, feedback mechanisms and other elements by way of databuses or other communication links.
Despite the efficacy of automatically performing sequences of operations, there are situations in which these automatic sequences should be terminated. In particular, these sequences should be terminated when either (a) the external circumstances in which the work vehicle is operating change to such an extent that the operations being performed are no longer appropriate or (b) one or more components of the work vehicle itself malfunction such that the automatic sequences would not produce the desired results if continued. For these situations, the work vehicle should include a mechanism whereby these automatic sequences are discontinued.
Work vehicles capable of such automatic sequences of operations may include a manual override feature whereby the operator may stop the automatic sequences by, for example, pressing a manual override switch. However, this type of feature is only of limited use in assuring that automatic sequences are stopped under the situations mentioned above. The operator of a work vehicle may not always observe, or even be capable of observing, whether external circumstances have changed to such an extent that a given automatic sequence of operations is inappropriate. Moreover, the operator of a work vehicle is even less likely to observe (or to be capable of observing) that particular components of the vehicle itself are malfunctioning while automatic sequences of operations are taking place. This is true not only with respect to malfunctioning electrical components of the work vehicle, but also with respect to mechanical elements, which may be deeply embedded within the work vehicle.
Accordingly, it would be advantageous to develop a system for automatically performing a sequence of operations in a work vehicle that includes an apparatus for automatically terminating the automatic sequence without manual input from the vehicle operator. It would also be advantageous if this apparatus were capable of stopping automatic sequences in response to a variety of conditions as determined by sensors and other devices, where such conditions would include the operational status of a variety of internal components. It would further be advantageous if this apparatus were easily modifiable so that the apparatus could be made responsive to additional conditions relating to devices added to the work vehicle, at a later date.